1. Field of the Invention
This invention relates to a tape carrier and a method of manufacturing the tape carrier for use with semiconductor apparatus, and more particularly to a tape carrier for the TAB (Tape Automated Bonding) technique and a method of manufacturing the tape carrier.
2. Related Prior Art
FIG. 11 is a perspective view showing a conventional tape carrier for semiconductor apparatus and FIG. 12 is a cross-sectional view of FIG. 11. In these drawings, a tape base 1 of the tape carrier is formed of, for example, polyimide resin with a thickness on the order of 75 .mu.m to 125 .mu.m. The tape base 1 has formed therein device holes 3 in the form of openings where semiconductor elements (not shown) are placed, and perforations 2 as positioning holes used to transport the tape carrier. Inner leads (and wirings) 4 to be connected with electrodes of the semiconductor element have one end projecting into each of the device holes 3 and another end connected to test electrodes 5 used for testing the semiconductor element. The inner leads 4 and the test electrodes 5 are formed of a material such as Cu and bonded to the tape base 1 by an adhesive 6, with Sn, Ni/Au or the like plated on their surfaces.
Conventional tape carriers are constructed as stated above, and the tape carrier shown in FIGS. 11 and 12 is manufactured through the steps shown in FIGS. 13 to 16. First, an adhesive 6 is applied to the tape base 1 shown in FIG. 13, as shown in FIG. 14. Next, the device holes 3 and the perforations 2 are cut as shown in FIG. 15 by punching using dies or the like. Then, a metal foil 7 made of Cu or the like is pasted in place as shown in FIG. 16, following which the metal foil 7 is subjected to photoengraving, etching, etc. to form the inner leads 4 and the test electrodes 5 as shown in FIG. 12. Finally, Sn, Ni/Au or the like is plated on the surfaces of the inner leads 4, thereby completing manufacture of the tape carrier.
Another tape carrier shown in FIG. 17 basically has the same construction as that shown in FIG. 12 except that, in the tape carrier of FIG. 17, the inner leads 4 are directly attached to the tape base 1 without using the adhesive 6. A method of manufacturing the tape carrier shown in FIG. 17 will be explained with reference to FIGS. 18 to 23. First, a metal thin film 7a of Cu or the like is formed by sputtering on the tape base 1 of FIG. 18, as shown in FIG. 19. Next, the device holes 3 and the perforations 2 are formed as shown in FIG. 20 by photoengraving, etching, etc. Subsequently, as shown in FIG. 21, a photoresist pattern 8 is formed at locations other than those where the inner leads 4 are to be provided, following which a metal thin film 7b of Cu or the like is disposed to a thickness on the order of 20 .mu.m to 30 .mu.m by a process such as electrolytic plating as shown in FIG. 22. Then, the photoresist pattern 8 is removed as shown in FIG. 23 and extra thin film portions 9 are etched away to produce the tape carrier shown in FIG. 17. Finally, Sn, Ni/Au or the like is plated on the surfaces of the inner leads 4, thereby completing manufacture of the tape carrier.
In the above tape carriers, with an increase in the number of pins and the processing speeds of semiconductor elements, there has not only become stronger a demand for a reduction in the component size of the tape carriers, but also a demand for increasing the number of layers of the tape carriers in order to reduce the inductance of the wiring. Because of the foregoing construction, however, the conventional tape carriers have difficulties meeting these demands.
More specifically, in the case of the tape carrier shown in FIG. 12, since holes cannot be formed in the tape base 1 by etching, it is not possible to form openings having dimensions less than 100 .mu.m.phi.. As regards to the multi-layer structure, a two-layer tape carrier can be manufactured by forming conductor patterns on the rear side of the tape base 1, but tape carriers having three or more layers have been difficult to manufacture. Further, metal foils of Cu or the like as thick as 20 .mu.m to 30 .mu.m must be etched, which leads to difficulties in etching those metal foils with a line width of 20 .mu.m to 30 .mu.m, for example, and hence a problem in reducing the pattern size.
In the case of the tape carrier shown in FIG. 17, there has been a problem that with patterns of small size, adhesion between the photoresist and the underlying metal layer is poor and the underlying metal layer tends to peel off. Particularly, if the underlying metal layer is as thin as 50 .mu.m to 75 .mu.m and hence weak in mechanical strength, the underlying metal layer may peel off while being transported for the purpose of etching the tape base 1. Further, although the two-layer structure is feasible from the viewpoint of practical construction, there have similarly been difficulties in realizing three or more layers because the tape base is too thick to form openings small in size.